The Prime Minister and Deputy Prime Minister will make a rare joint appearance to announce a host of pledges on childcare bills, infrastructure investment and help towards care costs for the elderly.

In an echo of the now infamous rose garden press conference that launched the power-sharing Government, they will set their new priorities for the next two-and-a-half years.

They will insist their sense of shared purpose on the big issues has "grown over time" as they publish a mid-term review that looks back at how successful the Government has been in meeting its coalition agreement promises and commits them to further reforms.

In a joint forward to the report, the PM and Deputy Prime Minister wrote: "We are dealing with the deficit, rebuilding the economy, reforming welfare and education and supporting hard-working families through tough times. And on all of these key aims, our parties, after 32 months of coalition, remain steadfast and united.

Clegg and Cameron at the launch of the Coalition

"Of course there have been some issues on which we have not seen eye to eye, and no doubt there will be more. That is the nature of coalition. But on the things that matter most - the big structural reforms needed to secure our country's long-term future - our resolve and sense of shared purpose have, if anything, grown over time."

The review, which aides insist is not a relaunch, promises to help families with their childcare costs amid speculation working parents with children under five will receive financial support.

It also pledges to "provide dignity in old age" with an improved state pension and help towards the cost of long term care. That follows a review by economist Andrew Dilnot, which recommended setting a care bill limit of between £25,000 and £50,000 to stop pensioners being forced to sell their homes to cover costs but the Government has looked at a number of options, including a £75,000 limit.

The joint forward states: "Today, at the half-way point in this parliament, we are taking stock of the progress we have made in implementing the coalition agreement that we signed in May 2010. But we are also initiating a new set of reforms, building on those already under way, to secure our country's future and help people realise their ambitions.

"We will support working families with their childcare costs. We will build more houses and make the dream of home ownership a reality for more people.

"We will set out plans for long-term investment in Britain's transport infrastructure. We will set out two big reforms to provide dignity in old age: an improved state pension that rewards saving, and more help with the costs of long-term care.

"And as we take these steps to reshape the British state for the 21st century, we will take further steps to limit its scope and extend our freedoms. We will be making announcements about each of these policy initiatives in due course.

"Our mission is clear: to get Britain living within its means and earning its way in the world once again.

"Our approach is consistent: to help hard-working families get by and get on, so that everyone can reach their full potential.

"And our resolve is unwavering: we will continue to put political partisanship to one side to govern in the long-term interests of the country."

The two leaders list welfare reforms, tougher school standards, council tax freezes, protecting the NHS from spending cuts and help with energy bills, fuel duty cuts and increases in the personal income tax allowance among the Government's achievements.

They add: "Two-and-a-half years ago, our parties came together in the national interest and formed a coalition at a time of real economic danger. The deficit was spiralling out of control, confidence was plummeting, and the world was looking to Britain with growing anxiety about our ability to service our debts.

"This Government's most urgent job was to restore stability in our public finances and confidence in the British economy. In just two years we have cut the deficit by a quarter and have set out a credible path towards our goal to balance the current budget over the economic cycle."

He told BBC1's Andrew Marr Show: "I want to fight the next election as the leader of the Conservative Party, I want to win a Conservative majority and I want to serve."

Asked whether that meant staying for five years he replied: "That's exactly what I have said."

He added: "Far from running out of ideas, we have got a packed agenda, which concerns things like how do we build roads in Britain to make sure our economy keeps moving, how do we pay for the care for the elderly, how do we have a pension system that encourages saving - big things that are going to equip our country for the next decade."

The Prime Minister also defended controversial cuts to child benefit payments for higher earners that come into effect at midnight, insisting the reforms were "fundamentally fair".

He also suggested it should be harder for European Union migrants to come to the United Kingdom and claim benefits.

He told the BBC programme: "Should we look at arguments about should it be harder for people to come and live in Britain and claim benefits? Yes, frankly, we should - so there are areas even in the free movement of people where we might want to make changes.

"We have got this balance of competencies review but all of these areas should be carefully looked at."